The Washington Capitals have played 33 "Game 3's" in their post season history (in seven-game series). It is a point in a series in which the Caps have not been very successful. Of those 33 instances, they lost 23 times. And in those series in which they lost Game 3, their series record is 6-17.
Washington has lost Game 3 in each of the last five post season series in which they played, winning two of those series (in five games against the New York Rangers in 2011 and in seven games against the Boston Bruins in 2012). They lost Game 3 three times in those last five instances, going on to lose in a four-game sweep to Tampa Bay in 2011, then twice losing in seven games to the Rangers (in 2012 and 2013).
Winning Game 3 is kinder to the Caps. In the ten instances in which they won Game 3 in a playoff series, the Caps have a 5-5 record in the series. The thing here is, the Caps have only two Game 3 wins out of 13 Games 3 played since they beat the Buffalo Sabres in Game 3 of the 1998 Eastern Conference final and went on to defeat the Sabres in six games to advance to the team's only Stanley Cup final. They defeated the Rangers in Game 3 of their 2009 meeting, the Caps going on to win the series in seven games. The Caps beat the Montreal Canadiens in Game 3 of their 2010 series, but it was the Canadiens who would advance, winning that series in seven games.
One thing that fans might count on, the game will be close. Six of the last seven Games 3 played by the Caps were one-goal games, one of them a three-overtime loss to the Rangers in 2012.
Decades of history are not the best predictor of results today; after all, many of these players had not been born when the Caps lost Game 3 of the 1984 Patrick Division final to the New York Islanders (a series the Islanders won in five games). Still...it would be a lot better winning this game than losing it, but you knew that already.